I have 15 HDDs in total , all of them are in 2.5 form factor : 2 Fujitsu 500GB , 1 WD Blue 1TB , 1 Hitachi (HGST) 1.5TB , 4 Samsung 1TB , 2 Seagate 2TB and 500GB, the rest are Toshiba 1TB drives
If Fujitsu did not go out of HDD business , I would say Fujitsu is the most reliable brand IMO
My first hard drive is Fujitsu MJA2500, I bought it in 2009 and it's still running strong till now
3 out of 4 Samsung drives were dead along side with my anime collection :/ and I could not recover anything. At this point, I think Samsung is the worst HDD manufacturer ever
Seagate is a hit and a miss. One drive failed but after I reformat the drive , it works again
Toshiba , WD Blue , Hitachi . These drives are still working after 3-4 years of usage
I don't know what's wrong with Seagate and Samsung though it might be just luck of a draw (assuming my luck was bad)

All the drives in my machine are WD, but I regularly hear good things about HGST ones (I have several external ones of theirs). As WD currently own HGST, until recently I'd been under the impression that their quality should be the same, hence going for WD when it was cheaper for the same spec. Apparently they do still use different factories and designs, though, so the quality difference does exist.

OS: Windows 10 64 bit Professional
CPU: Intel i5 4670K @3.4GHz... for now @4.6GHz with a quick and dirty (yet stable) OC. May get faster in a bit before the end of time.
RAM: 16GB (Down from 24 GB after some was given to siblings)
GPU: Radeon Vega 56

I got a 1TB Samsung Spinpoint HD103SJ still going strong since 2011-ish. I got myself a Seagate 3TB drive 6 months ago and so far no complaints. Also got a 2.5" external 2tb Seagate drive a year ago and no complaints there either.
OS is on a Samsung Evo 840 120GB SSD.

I can't really nominate one brand as a favorite yet, but I've had one bad experience with an external WD drive. Returned it immediately.

I had a Seagate 2TB drive die out of nowhere one day, taking my entire anime collection with it. It was only a year or two old, too. I haven't really trusted Seagate after that, but I have 3 WD drives now, and they all work beautifully.

Don't really have a "favorite" HDD Brand. Just buy what's the best price at the time for the most part. I've only had one HDD completely fail on me and it was due to being dropped during use...

I've had others come DOA though.

To be honest, most of the opinions I've seen on the internet about this rely on anecdotal evidence. Due to the nature of HDDs and the way they're distributed, just about everyone's going to get a bad egg sooner or later. I guess, what matters the most is whether the distributor or manufacturer will replace them without a hassle.

Although I never used Seagate HDDs, I already heard a lot of complaints (12 complaints, to be exact) of them dying out of nowhere from close friends. From those 12 friends, 6 bought Samsung HDDs as replacement, and well, after around 4 months they all complained about them overheating (?), generally dying a short time after the incident.

Besides that, I have an external 2.5" Toshiba HDD (bought 6 years ago), my HTPC has an 3.5" WD HDD even older (8 years) and on my laptop I have a 2.5" HGST running for 3 years (and counting). All of them are working trouble free and I never had issues until now, the only thing I could complain is that the HGST from my laptop always sounded too noisy for my tasting, at least when comparing to the others.

So, overall, Samsung and Seagate are the ones that gives most problem (based on what I heard -- also, apparently they both have merged?). That's a bummer since AFAIK only Seagate manufactures 2.5" HDDs of standard thickness at 2 TB size, and I'm looking forward doubling the HDD from my laptop soon...